Functional fluid composition for improving lubricity of a braking system

ABSTRACT

The functional fluids of the present invention comprise about 50 parts by weight to about 99 parts by weight of a glycol component and about 0.3 parts by weight to about 10 parts by weight of one or more additives including a phosphate content. Desirably, in one aspect of this invention, the functional fluid composition exhibits an average scar width according to ASTM D 2670 (100 lb break-in for 1 min, 200 lb load for 30 minutes) that ranges from about 0.05 mm to about 0.45 mm, an average tooth count according to ASTM D 2670 (100 lb break-in for 1 min, 200 lb load for 30 minutes) of less than about 15, or both.

CLAIM OF PRIORITY

The present application claims the benefit of the filing date ofProvisional Application No. 60/979901 (“FUNCTIONAL FLUID COMPOSITION FORIMPROVING LUBRICITY OF A BRAKING SYSTEM” filed Oct. 15, 2007 by Zhao et.al.), the contents of which are hereby incorporated by reference intheir entirety.

FIELD OF THE INVENTION

This invention relates to functional fluids that are useful in a varietyof applications. The functional fluids of the present invention areparticularly useful as hydraulic fluids such as brake fluids foranti-lock brake systems, stability control systems or regenerativebraking systems for automotive vehicles that benefit from lowerviscosity fluids for sudden movement (e.g., sudden braking),satisfactory operation, or both at low temperatures.

BACKGROUND OF THE INVENTION

Newly developed equipment such as electronic or automated anti-lockbraking systems, stability control systems and regenerative brakingsystems have created a need for high performance hydraulic fluids (e.g.,brake fluids) having appropriate physical and performance properties. Inparticular, there is a strong demand for high performance brake fluidshaving high lubricity to reduce or eliminate brake noise, whileimproving the life of the brake. Additionally, there is a demand forhigh performance brake fluids having good low temperature viscositieswhile meeting or exceeding the desired minimum dry equilibrium refluxboiling point (ERBP) and wet equilibrium reflux boiling point (WERBP)temperatures. Illustrations of current international standards for brakefluids are set forth in Table 1 below. Successful candidates for suchfluids need to be relatively inexpensive too.

One exemplary solution to providing such desirable functional fluids wasintroduced in commonly owned U.S. Patent Application Publication2007/0027039, filed Jun. 29, 2006, titled Low Viscosity FunctionalFluids, and incorporated herein by reference for all purposes.

SUMMARY OF THE INVENTION

In one aspect, the invention is directed at a functional fluidcomposition for imparting lubricity in a fluid power system havingmetal/rubber contact comprising: about 50 parts by weight to about 99parts by weight of a glycol component; and about 0.3 parts by weight toabout 10 parts by weight of one or more additives including a phosphatecontent; wherein the functional fluid composition exhibits an averagescar width as measured according to ASTM D 2670 (100 lb break-in for 1min, 200 lb load for 30 minutes) less than about 0.35 mm, an averagetooth count according to ASTM D 2670 (100 lb break-in for 1 min, 200 lbload for 30 minutes) of less than about 15, or both, and wherein thefunctional fluid is optionally free of silicone; wherein the one or moreadditives includes either or both of a first additive including an esterof phosphoric acid and/or a second additive including an ethoxylatedphosphate ester.

TABLE 1 DOT 3, DOT 4 and DOT 5 Brake Fluid Standard Standard FMVSS FMVSSISO FMVSS ISO 4925 116, SAE 116, SAE 4925 116, ISO 1703, ISO, 1704 49254925 Classification (FMVSS, DOT 3 DOT 4 DOT 5.1 SAE) Classification(ISO) Class 3 Class 4 Class 5.1 Class 6 ERBP Min 205° C. Min 230° C. MinMin 260° C. Min 250° C. 205° C. Wet ERBP (3.5% Min 140° C. Min 155° C.Min Min 180° C. Min 165° C. water per FMVSS 116) 155° C. KINEMATIC max.1500 cSt max. 1800 cSt max. max. 900 cSt Max. 750 cSt VISCOSITIES 1500cSt at 40° C.

This aspect of the invention may be further characterized by one or anycombination of the following features: the first additive consistsessentially of a tricresyl phosphate; the second additive includes anethoxylated phosphate ester selected from the group consisting of apolyoxyethylene octadadecenyl ether phosphate. a polyoxyethylene laurylether phosphate, a linear alcohol ethoxy phosphate, a polyethylenephenyl ether phosphate, a dialkylphenol phosphate ester or anycombination thereof; the second additive includes a polyethylene glycolphenyl ether phosphate; the second additive consists essentially of apolyethylene glycol phenyl ether phosphate; the first additive exhibitsa melting point that ranges from about −45° C. to about −25° C., aboiling point (at 4 mm Hg) that ranges from about 230° C. to about 265°C., a flash point that is at least about 375° C., a specific gravity (at25° C.) that ranges from about 1.1 to about 1.25, and an acid number ofless than about 0.5 mg KOH/kg of the first additive; the second additiveexhibits an acid number (KOH to first inflection point) that ranges fromabout 90 to about 115 mg KOH/kg of the second additive and a nonioniccontent less than about 15%; the first additive, the second additive, orboth is present in the amount of about 0.005 to about 0.7 parts byweight of the fluid composition; the one or more additives includes acorrosion inhibitor that is present in the amount of about 0.5 parts byweight to about 2 parts by weight of the one or more additives; the oneor more additives further comprises an antioxidant, an anti-foamingagent, a pH stabilizer, or any combination thereof; the glycol componentcomprises the formula:

wherein R₁ is H or an alkyl group containing 1 to 8 carbon atoms ormixtures thereof, the glycol component including at least one glycolwherein at least one of R₂, R₃, R₄, and R₅ is an alkyl group containing1 to 8 carbon atoms; the glycol component includes at least one glycolwherein R₂, R₃, R₄, and R₅ are each H; the glycol component includes atleast one glycol having at least one first repeat unit wherein R₂, R₃,R₄, and R₅ are each H and at least one second repeat unit wherein atleast one (e.g., one, two, three, or all four) of R₂, R₃, R₄, and R₅ areeach an alkyl group containing 1 to 8 carbon atoms; the at least oneglycol include glycol where n=2 is present in an amount of from about0.25 parts by weight to about 10 parts by weight of the glycol componentand glycol where n=4 or more in an amount from about 0 parts by weightto about 30 parts by weight of the glycol component; the composition issubstantially free of glycol borate esters; the fluid compositionfurther comprises from about 0.1 parts by weight to about 70 parts byweight of a glycol borate ester comprising the formula:

wherein each R₁ R₂, R₃, R₄, and R₅ is independently H or an alkyl groupcontaining 1 to 8 carbon atoms or mixtures thereof, n is 1 to 4; theamount of the borate ester with n=3 is greater than about 90 parts byweight of the borate ester, an amount of the borate ester with n=2 isfrom about 0.5 parts by weight to about 5.0 parts by weight of theborate ester, and an amount of the borate ester with n=4 is from about 0or 0.1 parts by weight to about 15 parts by weight of the borate ester;the amount of glycol component with n=3 is greater than about 40 partsby weight of the glycol component, an amount of glycol component withn=2 is from about 0.5 parts by weight to about 5.0 parts by weight ofthe glycol component, and the glycol component with n=4 or more is fromabout 5 parts by weight to about 15 parts by weight of the glycolcomponent; the glycol component comprises one or more high purity glycolcomponents; about 0.5 parts by weight to about 10 parts by weight of theglycol component has R₁ contains 4 carbon atoms and n=2, about 40 partsby weight to about 60 parts by weight of the glycol component has R₁contains 1 carbon atom and n=3, about 5 parts by weight to about 15parts by weight of the glycol component has R₁ contains 4 carbon atomsand n=3, about 5 parts by weight to about 15 parts by weight of theglycol component wherein R₁ contains 4 carbon atoms and n=4 or more,about 0.3 parts by weight to about 10 parts by weight of one or moreadditives including a phosphate content, and the functional fluidcomposition exhibits either or both of an average scar width accordingto ASTM D 2670 (100 lb break-in for 1 min, 200 lb load for 30 minutes)that ranges from about 0.1 mm to about 0.3 mm or an average tooth countaccording to ASTM D 2670 (100 lb break-in for 1 min, 200 lb load for 30minutes) of less than about 8; the functional fluid composition is freeof silicone; the fluid power system is a brake system; the one or moreadditives further includes at least one corrosion inhibitor, the atleast one corrosion inhibitor is present in the amount of about 0.005 toabout 5 parts by weight of the additive component.

Another aspect of the invention is directed at an additives package forimparting lubricity in a fluid power system comprising: about 5 parts byweight to about 75 parts by weight of at least one of (i) a firstadditive including an ester of phosphoric acid and (ii) a secondadditive including an ethoxylated phosphate ester; about 30 parts byweight to about 99 parts by weight of two or more corrosion inhibitorsthat includes at least one of (a) propanediamine and xylene, (b)hydroxyethylpiperazine, (c) dodecenyl succinic anhydride, (d)Di-(2-ethylhexyl)phosphoric acid, (e) poly(diethoxysiloxane), (e) oleicacid, and (f) propylene glycol and borax 5 mol component, wherein thefirst additive exhibits a melting point that ranges from about −45° C.to about −25° C., a boiling point (at 4 mm Hg) that ranges from about230° C. to about 265° C., a flash point that is at least about 375° C.,a specific gravity (at 25° C.) that ranges from about 1.1 to about 1.25,and an acid number of less than about 0.5 mgKOH/kg, wherein the secondadditive exhibits an acid number (KOH to first inflection point) thatranges from about 90 to about 115 and a nonionic content less than about15%, and wherein a functional fluid composition includes the additivepackage, the functional fluid composition exhibits an average scar widthaccording to ASTM D 2670 (100 lb break-in for 1 min, 200 lb load for 30minutes) of less than about 0.35 mm, an average tooth count according toASTM D 2670 (100 lb break-in for 1 min, 200 lb load for 30 minutes) ofless than about 15, or both.

This aspect of the invention may be characterized by one or anycombination of the following features: the first additive consistsessentially of a tricresyl phosphate; the second additive consistsessentially of a polyethylene glycol phenyl ether phosphate.

A further aspect of the invention is dericted at a functional fluidcomposition for imparting lubricity in a fluid power system havingmetal/rubber contact comprising: about 50 parts by weight to about 99parts by weight of a glycol component; and about 0.3 parts by weight toabout 10 parts by weight of one or more additives; wherein thefunctional fluid is further characterized either or both of the glycolcomponent includes a polyethylene-propylene glycol monomethyl etherhaving an average molecular weight of about 500 at a concentration fromabout 10 wt. % to about 30 wt. % based on the total weight of thefunctional fluid; or the one or more additives includes oleic acid at aconcentration from about 0.02 wt. % to about 0.5 wt. % based on thetotal weight of the functional fluid; wherein the one or more additivesoptionally contains a polyethylene phenyl ether phosphate, thefunctional fluid is optionally is free of silicone, the glycol componentincludes methoxytriglycol present a concentration greater than about 25wt. % based on the total weight of the functional fluids, and thefunctional fluid has one or any combination of the followingcharacteristics: an average scar width less than about 0.36 mm, a toothcount less than about 10, an ERBP greater than about 250° C., or aviscosity at −40° C. of less than about 800 cSt.

A process aspect of the invention is direct at method for impartinglubricity comprising the steps of: contacting one or more rubbercomponents of a fluid power system with a functional fluid compositionfree of silicone and including about 0.3 parts by weight to about 10parts by weight of one or more additives including a phosphate content,wherein the functional fluid composition exhibits either or both of anaverage scar width according to ASTM D 2670 (100 lb break-in for 1 min,200 lb load for 30 minutes) that ranges from about 0.05 mm to about 0.45mm and/or an average tooth count according to ASTM D 2670 (100 lbbreak-in for 1 min, 200 lb load for 30 minutes) of less than about 15.

Another aspect of the invention is directed at a braking system whichincludes a functional fluid composition and/or an additives package asdescribed herein. Such a braking system may further be characterized asbeing free of a booster.

Yet another aspect of the invention is directed at the use of afunctional fluid composition and/or an additives package as describedherein in a braking system. Such a braking system may be furthercharacterized as being free of a booster.

DETAILED DESCRIPTION OF THE INVENTION

The present invention contemplates an improved composition possessing aunique combination of attributes that make it suitable as a workingfluid in a number of applications, especially in hydraulic fluidsapplications (e.g., a fluid which is in a sealed and/or closed system inwhich the fluid may be exposed to temperatures greater than about 50°C., or even greater than about 100° C., and may remain in a liquid stateat those temperatures), such as brake fluids. More particularly, thefluid compositions of the present invention employ a glycolic componentas its major component and preferably also include one or moreadditives. Surprisingly, when the compositions are employed as describedherein, the fluids exhibit a high lubricity, high dry equilibrium refluxboiling point (ERBP), a low temperature viscosity, a low average scarwidth as measured according to ASTM D 2670 with a 45.4 kg break-in for 1minute followed by a 90.9 kg load for 30 minutes, and/or a low averagetooth count as measured according to ASTM D 2670 (with a 45.4 kgbreak-in for 1 minute followed by a 90.9 kg load for 30 minutes (allsuch properties being in accordance with the preferred properties asdescribed herein). More specifically the present invention employs aglycol component of glycols, alkoxy glycols, or both, and an additiveincluding a phosphate content (such as an ester of phosphoric acidand/or an ethoxylated phosphate ester) that together provide a fluidthat can be used as a brake fluid, which meets the provisions for of oneor both of DOT 3 or DOT 4 brake fluids under the provisions of the tableabove. By way of example, unexpectedly good results are believedobtainable (e.g., in a brake fluid composition that may be free ofsilicone) when employing as a composition of the present invention, incombination with a glycolic major component (e.g., a glycol componentincluding an alkoxyl triglycol such as methoxytriglycol, butoxytriglycolor both, and optionally an alkoxylated polyethylene-propylene glycoland/or an alkoxylated polypropylene glycol), one or both of a firstadditive including (or consisting essentially of, or even consisting of)an ester of phosphoric acid (e.g., an aromatic phosphate ester such astricresyl phosphate), or a second additive including (or consistingessentially of, or even consisting of) an ethoxylated phosphate ester(e.g., one that includes an ethoxylated phosphoric ester and/or apropoxylated phosphoric ester, such as polyoxyethylene octadadecenylether phosphate, polyoxyethylene lauryl ether phosphate, a linearalcohol ethoxy phosphate, a polyethylene phenyl ether phosphate, adialkylphenol phosphate ester, or any combination thereof.

The use of an additive including a phosphate content (such as the firstadditive and/or the second additive), without beyond bound by theory, isbelieved to improve the lubricity of the fluid and reduce the averagescar width and/or reduce the average tooth count. Such additives havebeen used as working fluids in metal working operations, such as metalrolling and metal forming which are generally performed in open systemswhere the fluid can expand and the fluid is not exposed to repeatedoperations (e.g., more than one, two or three forming steps at the sameregion, and/or the fluid is not exposed repeatedly to temperaturesgreater than about 50° C. or greater than about 100° C.). Anti-wearadditives including a phosphate content have also been used in otherapplications, such as in refrigerant compositions, which generallycontain a high concentration of a refrigerant (e.g., a fluorocarboncontaining fluorine, carbon and optionally other atoms such as hydrogenand chlorine, which typically have a boiling point below 60° C.,preferably below about 50° C. or even below 30° C.). Refrigerant systemstypically operate at relatively low pressures, e.g., less than about 10,4 or even 2 atmospheres). Functional fluids for systems such as brakesystems are very demanding in that the fluid may be repeatedly exposedto high temperatures (e.g., greater than about 60, 80, 100, or even 120°C.) and/or high pressures, greater than about 10, 20, 50, or 100atmospheres. This is particularly true for glycolic functional fluidcompositions as compared with silicone based functional fluidcompositions, as the silicone fluids are innately more stable andrelatively more expansive. Brake fluids (which are generally free ofrefrigerants, such as a fluorocarbon containing fluorine, carbon andoptionally other atoms) are typically exposed to repeated pressureand/or temperature cycles. The number of cycles may be quite high (e.g.,greater than 10, 100, 1000 or even 10000), as the fluid may be replacedonly once every year or even less. Additionally, the changes in pressuremay be quite sudden (e.g., some or even all of the fluid may increase inpressure from less than 2 atmospheres to greater than 10 atmospheres ina time of less than 1 or even less than 0.1 second). The changes intemperature may also be quite severe, with the temperature sometimesstarting near or at ambient conditions (which typically is less thanabout 30° C., but may be less than about 0° C., or even less than about−30° C.). It is found that the additives containing a phosphate content(as described herein) offer surprising benefits, including wearresistance properties, in a demanding application such as brake fluidswhich experiences repeated pressure loading and unloading, repeatedthermal heating (e.g., due to the friction between a moving componentand a braking component). It is believed that these results areunexpected in a glycolic functional fluid (e.g., a fluid which issubstantially free, or even entirely free of a refrigerant and/orsilicone) used in a brake system which is a closed, sealed system whichrepeatedly experiences temperature and pressure changes as describedabove.

Functional fluids of the present invention may comprise one or anycombination of the following:

-   -   (a) about 50 parts by weight to about 99 parts by weight, based        on the total weight of the composition of a glycol component;    -   (b) optionally, about 0 parts by weight to about 70 parts by        weight, based on the weight of the total composition, of a        glycol borate ester component; and    -   (c) about 0.30 parts by weight to about 10 parts by weight,        based on the weight of the total composition, of an additive        component (e.g., an additive component including a phosphate        content).

The glycol component can be formed partially, substantially entirely (atleast 90% or at least 95% by weight) or entirely of one, two, three ormore glycols, polyglycols, or both. Preferably the glycols orpolyglycols of the glycol component have the formula of FORMULA I:

with repeat unit:

Each of R₁, R₂, R₃, R₄, R₅ is either hydrogen (H) or an alkyl groupcontaining 1 to 8 or more carbon atoms or mixtures thereof. For example,the glycols or polyglycols may have at least one of R₂, R₃, R₄, R₅ is analkyl group containing 1 to 8 or more carbon atoms, such as onedisclosed in Provisional Application Ser. No. 60/976,010 (filed Sep. 28,2007) titled “Functional Fluid Composition”, which is herebyincorporated by reference for all purposes. It is preferable that R₁ bean alkyl group containing 1 to 8 carbon atoms such that glycol orpolyglycol is an alkoxy glycol ether (e.g., an alkyl end capped alkoxyglycol ether) as opposed to being simply a glycol where R₁ is (H).Typically, R₁ is (H) for less than 90%, more typically less than 50% andeven possibly less than 30% or 20% by weight of the glycol component,the overall fluid composition, or both. It will be understood that, asused herein, a polyglycol of FORMULA I has n of at least 2 or greaterand that the term glycol includes all polyglycols. It should also beunderstood that the glycol component can include glycols or FORMULA Iwherein R₁ is an alkyl group and where R₁ is H.

The glycols of FORMULA I having n of at least 2 may have repeat unitswhich are the same (e.g., a homopolymer), repeat units which aredifferent (e.g., a copolymer), or a combination thereof. Polyglycolcopolymers may include two, three or even four or more different repeatunits. A preferred copolymer may contain two different repeat units.Polyglycol copolymers may be characterized as block copolymers, randomcopolymers, alternating copolymer, or any combination. Block copolymersmay include copolymers having one block of each repeat unit, as well ascopolymers having a plurality of blocks of one or even each of therepeat units. A block may be defined as a long run of consecutivesequences (e.g., three, four, five, or more) of the same repeat units.Suitable polyglycol copolymer include random copolymers such as acopolymer which is substantially free (e.g., less than about 20 mole %,or even 10 mole % of the repeat units of the copolymer are in blocks) oreven entirely free of blocks of long run of consecutive sequences (e.g.,three, four, five, or more) of the same repeat units. Withoutlimitation, exemplary glycols include those in which the repeat unit isethylene oxide (CH₂—CH₂—O), propylene oxide (e.g., CH(CH₃)—CH₂—O orCH₂—CH(CH₃)—O), or combinations thereof.

The glycol component may include an amount of glycol where n=1. Whenincluded, such glycol is at least about 5% by weight of the glycolcomponent. Moreover such glycol is typically less than about 30%, moretypically less than about 20% and even more typically less than about15% by weight of the of the glycol component. Preferably, glycols of theglycol component comprise glycols (e.g., alkoxy glycols) where n=2,glycols (e.g., alkoxy glycols) where n=3, glycols (e.g., alkoxy glycols)where n=4 or more, or any mixture thereof. More preferable glycolcomponents may comprise a combination (e.g., a mixture) of glycols(e.g., alkoxy glycols) having n=2, n=3, and n=4 or more. It is alsopreferred for the glycols wherein n=2 or more to be present in theglycol component and/or the overall functional fluid in an amount thatis at least about 50 parts by weight, more typically at least about 60parts by weight and more typically at least about 75 parts by weight ofthe glycol component, the overall functional fluid or both. It is alsopreferred for the glycols wherein n=2 or more to be present in theglycol component and/or the overall functional fluid in an amount thatis less than about 99 parts by weight, more typically less than about 90parts by weight and even more typically less than about 85 parts byweight.

The glycol component typically includes an amount of one or more firstglycol (e.g., a first polyglycol) where R₂, R₃, R₄, and R₅ are each H.When included, such first glycol is at least about 3%, more typically atleast about 10% and even more typically at least about 20% by weight ofthe glycol component. Moreover such first glycol is typically less thanabout 80%, more typically less than about 50% and even more typicallyless than about 30% by weight of the of the glycol component. For suchfirst glycol, n is at least 1, but preferably n is 2 or more. The amountof the first glycol in which n=2 is typically from about 0.25 parts byweight to about 20.00 parts by weight by weight of the first glycol. Theamount of the first glycol in which n=3 is typically from about 25.0parts by weight to about 99.5 parts by weight of the first glycol. Theamount of the first glycol in which n=4 is typically from about 0 or 0.1parts by weight to about 15 parts by weight of the first glycol. Ofcourse, higher or lower amounts of the overall first glycol and theparticular amounts of the first glycol having different n values may beemployed unless otherwise specified.

The glycol component may optionally include an amount of one or moresecond glycol (e.g., a second polyglycol) wherein at least one (andpreferably only one), but also possibly two, three or all four of R₂,R₃, R₄, and R₅ are each an alkyl group containing 1 to 8 carbon atoms.Preferable second glycols (which may be one glycol or a mixture ofglycols) include an R₂ or R₃ group and more preferably include an R₄ orR₅ group comprising a methyl, an ethyl, a propyl, a butyl, or anycombination thereof. Moreover, preferable second glycols include an R₂or R₃ group and more preferably include an R₄ or R₅ group comprising amethyl or an ethyl group. Still more preferable second glycols includean R₂ or R₃ group and more preferably include an R₄ or R₅ groupcomprising a methyl group. When included, such second glycol is at leastabout 3%, more typically at least about 10% and even more typically atleast about 20% by weight of the glycol component. Moreover such secondglycol is typically less than about 80%, more typically less than about50% and even more typically less than about 30% by weight of the of theglycol component. For such second glycol, n is at least 1, butpreferably n is 2 or more. The amount of the second glycol in which n=2is typically from about 0.25 parts by weight to about 10.00 parts byweight by weight of the second glycol. The amount of the second glycolin which n=3 is typically from about 25.0 parts by weight to about 99.5parts by weight of the second glycol. The amount of the second glycol inwhich n=4 is typically from about 0 or 0.01 parts by weight to about 15parts by weight of the second glycol. Of course, higher or lower amountsof the overall second glycol and the particular amounts of the secondglycol having different n values may be employed unless otherwisespecified.

The glycol component may optionally include an amount of one or morethird glycol (e.g., a third polyglycol) that is a copolymer. Suchcopolymer may be a block copolymer, and/or a random copolymer. Thus, anyof the third glycols (which may be one glycol or a mixture of glycols)will typically include one or more first repeat units of FORMULA Ihaving a first configuration and one or more second repeat units havinga second configuration. In particular, the third glycol typicallyincludes at least one of first repeat unit of FORMULA I wherein R₂, R₃,R₄, and R₅ are each H. The third glycol also typically includes at leastone second repeat unit wherein at least one and typically only one, butalso possibly two, three or all four of R₂, R₃, R₄, and R₅ are each analkyl group containing 1 to 8 carbon atoms. Preferable second repeatunits of the third glycols include an R₂ or R₃ group and more preferablyinclude an R₄ or R₅ group comprising a methyl, an ethyl, a propyl, abutyl, or any combination thereof. More preferable second repeat unitsof the third glycols include an R₂ or R₃ group and more preferablyinclude an R₄ or R₅ group comprising a methyl or an ethyl group. Stillmore preferable second repeat units of the third glycols include an R₂or R₃ group and more preferably include an R₄ or R₅ group comprising amethyl group. When included, such third glycol is at least about 3%,more typically at least about 10% and even more typically at least about20% by weight of the glycol component. Moreover, such third glycol istypically less than about 80%, more typically less than about 50% andeven more typically less than about 30% by weight of the of the glycolcomponent. For such third glycol, n is at least 2 or more. The amount ofthe third glycol in which n=2 is typically from about 0.25 parts byweight to about 10.00 parts by weight by weight of the third glycol. Theamount of the third glycol in which n=3 is typically from about 25.0parts by weight to about 99.5 parts by weight of the third glycol. Theamount of the third glycol in which n=4 is typically from about 0 or0.01 parts by weight to about 15 parts by weight of the third glycol. Ofcourse, higher or lower amounts of the overall third glycol and theparticular amounts of the third glycol having different n values may beemployed unless otherwise specified.

Advantageously, use of glycols of each of the types mentioned, butparticularly the second glycols and third glycols, surprisingly assistthe fluid in achieving various properties. Such properties can include,without limitation, higher boiling points, lower viscosities, greaterlubricity, combinations thereof or the like. Preferably the glycolcomponent includes a (e.g., one or more) second glycol, a (e.g., one ormore) third glycol, or both. The amount of the second glycol, the thirdglycol, or the combination of the second glycol and third glycol may begreater than about 5 wt. %, preferably greater than 10 wt. %, and morepreferably greater than about 15 wt. % based on the total weight of thefluid composition. The amount of the second glycol, the third glycol, orthe combination of the second glycol and third glycol may be less thanabout 90 wt. %, preferably less than about 70 wt. %, more preferablyless than about 50 wt. %, and most preferably less than about 35 wt. %based on the total weight of the fluid composition. Of course, higher orlower amounts of the second glycol, the third glycol, or the combinationof the second and third glycol may be employed

Suitable R₁ groups of the glycol component are alkyl groups containingfrom 1 to 8 carbon atoms. Preferable glycol components include an R₁group comprising a methyl, an ethyl, a propyl, a butyl, or anycombination thereof.

Without limitation, examples of useful glycols (e.g., alkoxy glycols orotherwise) include methoxy triglycol, methoxy diglycol, methoxypolyglycol, ethoxy triglycol, ethoxy diglycol, ethoxy tetraglycol,propoxy triglycol, butoxy triglycol (e.g., triethylene glycol monobutylether), butoxy diglycol (e.g., diethylene glycol monobutyl ether),butoxy teteraglycol, pentoxy diglycol, pentoxy triglycol, 2-ethylhexyldiglycol or any combination thereof.

Preferable glycols (e.g., alkoxy glycols) of the glycol componentinclude, without limitation, methoxy triglycol, methoxy diglycol,methoxy polyglycol, methoxy tetraglycol, ethoxy polyglycol, ethoxytriglycol, ethoxy diglycol, ethoxy tetraglycol, butoxy polyglycol,butoxy triglycol, butoxy diglycol, butoxy tetraglycol, triethyleneglycol monohexyl ether, diethylene glycol monopropyl ether, triethyleneglycol monopropyl ether, dipropylene glycol monomethyl ether,dipropylene glycol monopropyl ether, tripropylene glycol monopropylether, dipropylene glycol monobutyl ether, tripropylene glycol monobutylether, polypropylene glycol monobutyl ether, polypropylene glycolmonopropyl ether, or any combination thereof. More preferable alkoxyglycol components comprise methoxy triglycol, methoxy diglycol, methoxypolyglycol, butoxy triglycol, butoxy diglycol, butoxy polyglycol,Triethylene glycol monohexyl ether, Diethylene glycol monopropyl ether,Triethylene glycol monopropyl ether, Dipropylene glycol monomethylether, dipropylene glycol monopropyl ether, tripropylene glycolmonopropyl ether, dipropylene glycol monobutyl ether, tripropyleneglycol monobutyl ether, polypropylene glycol monopropyl ether,Polypropylene glycol monobutyl ether or any combination thereof. Mostpreferable alkoxy glycol components comprise a mixture of two or more ofmethoxy polyglycol, butoxy diglycol, butoxy triglycol, butoxypolyglycol, triethylene glycol monopropyl ether, tripropylene glycolmonopropyl ether, tripropylene glycol monobutyl ether, polypropyleneglycol monopropyl ether, or polypropylene glycol monobutyl ether.

Further examples of useful glycols (e.g., alkoxy glycols or the like)include, without limitation, diethylene glycol monopropyl ether,triethylene glycol monopropyl ether, dipropylene glycol monomethylether, dipropylene glycol monopropyl ether, tripropylene glycolmonopropyl ether, dipropylene glycol monobutyl ether, dipropylene glycolmonomethyl ether, tripropylene glycol monoethyl ether, tripropyleneglycol monopropyl ether, tripropylene glycol monobutyl ether,polypropylene glycol monopropyl ether, polypropylene glycol monobutylether, polybutylene glycol monopropyl ether, polybutylene glycolmonobutyl ether, any combinations thereof or the like.

Without limitation, methods of preparing useful alkoxy glycols includean alkoxilation reaction that reacts an alkylene oxide with an alcoholto produce an alkyl glycol.

In one aspect, use of high purity alkoxy glycols in the glycol componentis preferable. For example, by using high purity alkoxy glycol, asuitable low temperature viscosity is achievable. In particular, highpurity butoxy triglycol and butoxy diglycol may individually or incombination be used to help maintain the desired low temperatureviscosity. In one aspect, high purity alkoxy glycol is at least about90% pure (i.e., the high purity alkoxy glycol consists of at least about90 wt. % of molecules having the same molecular structure); at leastabout 97% pure, or at least about 98% pure. In one preferred embodiment,high purity butoxy triglycol and high purity butoxy diglycol is utilizedin the fluid composition and is preferably at least 50% and morepreferably at least 75% by weight of the glycol component.

The fluid composition may also include borate ester, but preferablyincludes no more than about 10 parts by weight of a borate ester (e.g.,a glycol borate ester) based on the weight of the fluid composition.Suitable fluid compositions may also be substantially free, or evenentirely free of a glycol borate ester. When utilized, the glycol borateester component preferably includes at least one ingredient that has theformula:

with repeat unit:

where R₁, R₂, R₃, R₄, and R₅ can be any of groups as specified withrespect to FORMULA I and n can be as specified with respect to FORMULAI, (for example, R₁ R₂, R₃, R₄, and R₅ may each independently be H or analkyl group containing 1 to 8 carbon atoms or mixtures thereof, and nmay range from 1 to 4). As such, the glycol borate ester component canhave any of the repeat units of the first glycol of the glycolcomponent, the second glycol of the glycol component, the third glycolof the glycol component or any combination thereof as discussed withrespect to FORMULA I herein. It is also understood that the glycolborate ester component and any borate containing compound is notconsidered as part of the glycol component, but rather is separate.

Examples of optional glycol borate ester components include alkoxyglycol borate ester components such as methoxy triethylene glycol borateester, ethoxy triethylene glycol borate ester, butoxy triethylene glycolborate ester or any combination thereof disclosed in U.S. Pat. No.6,558,569, filed Nov. 10, 2000 (see e.g., column 3, lines 13-40), herebyincorporated by reference. If a borate ester component is present in thecomposition, it is preferably present in an amount greater than 0.01 orgreater than 1 parts by weight of the functional fluid, but it is alsopreferably present in an amount less than about 10 parts by weight ofthe functional fluid. More preferably, the borate ester component ispresent in the composition in an amount less than about 4 parts byweight of the functional fluid. In one embodiment, the functional fluidcompositions of the present invention are substantially free (less thanabout 0.5% by weight of the functional fluid) or entirely free of anyborate ester component.

When a glycol borate component is in the composition, it is typicallythe case that the glycol groups represent a substantial portion of thecomposition. Such glycol groups, as defined herein, are the portions ofFORMULA I and FORMULA II attached to the (H) hydrogen atom or the (B)Boron atom of those formulas. Thus, such glycol groups may be asfollows:

These glycol groups can represent at least about 50%, more typically atleast about 60%, still more typically at least about 80% and evenpossibly at least about 90% by weight of the overall composition.

As indicated, the composition of the present invention furthercontemplates an optional additive package that includes one or moreadditives having a phosphate content (e.g., at least one phosphateester) for improving lubricity of a brake system. The additive componentadditives thus may comprise one or more additives that typically includeone or any combination, without limitation corrosion inhibitors,stabilizers such as pH stabilizers, lubricants, anti-wear agents,anti-foaming agents, and antioxidants. The additive component, whenpresent, is typically at least about 0.05 parts by weight, moretypically at least about 0.1 parts by weight and even more typically atleast about 0.3 parts by weight of the functional fluid. The additivecomponent, when present, is typically less than about 20 parts byweight, more typically less than about 15 parts by weight, and evenpossibly less than about 10 parts by weight of the functional fluid.

It will be appreciated from the above that the one or more additivesherein may have a phosphate content. For example, one preferred approachis to have one or more additives having a phosphate content present inthe amount of at least about 0.005, more specifically at least about0.01, and still more specifically at least about 0.1 parts by weight ofthe additive component. It is generally expected however that the totalconcentration of the one or more additives including phosphate will beless than about 0.7, more specifically less than 0.5, and morespecifically less than about 0.4 parts by weight of the additivecomponent.

The additives package of the present invention may include from about 5parts by weight to about 75 parts by weight (e.g., from about 5 wt. % toabout 75 wt. % based on the total weight of the additives package) of atleast one of (i) a first additive including an ester of phosphoric acidand (ii) a second additive including an ethoxylated phosphate ester andabout 30 parts by weight to about 99 parts by weight (e.g., from about30 wt. % to about 99 wt. % based on the total weight of the additivespackage) of two or more corrosion inhibitors that includes at least oneof (a) propanediamine and xylene, (b) hydroxyethylpiperazine, (c)dodecenyl succinic anhydride, (d) di-(2-ethylhexyl)phosphoric acid, (e)poly(diethoxysiloxane), (e) oleic acid, and (f) propylene glycol andborax 5 mol component.

In one preferred example for use in the additive component, the one ormore additives having a phosphate content will include a first additivehaving a phosphoric ester. The phosphoric ester may be an aromaticphosphate ester, an aliphatic phosphate ester, or a combination thereof,Without limitation, the phosphoric ester may be an aromatic phosphateester such as a phosphoric acid tris(methylphenyl)ester (e.g., tricresylphosphate). The first additive may have a specific gravity (at 20° C.)that ranges from about 1.1 to about 1.25 and a flash point of at leastabout 380° C. (e.g., about 390 to about 430° C. The first additive mayexhibit a melting point of less than about −55, and more specificallyless than about −45° C. The first additive may also exhibit a meltingpoint of at least about −25, and more specifically at least about −30°C. For example, the melting point may range from about −55 to about −25,and more preferably from about −45 to −30° C. The first additive mayexhibit a boiling point (at 4 mm Hg) of at least about 230, and morespecifically at least about 240° C. The first additive may also exhibita boiling point (at 4 mm Hg) of less than about 270, and morespecifically less than about 265° C. For example, the boiling point (at4 mm Hg) may range from about 230 to about 270, and more preferably fromabout 240 to 265° C. The first additive may exhibit an acid number,e.g., as measured according to ASTM D974-01, of less than about 0.5,more specifically less than about 0.1 mg KOH/kg.

In another preferred example for use in the additive component, the oneor more additives having a phosphate content includes a second additivehaving (or consisting of) an alkoxylated phosphoric ester. Suitablealkoxylated phosphoric esters, without limitation, an ethoxylatedphosphoric ester, a propoxylated phosphoric ester, and the like. Thealkoxylated phosphoric ester may contain one or more aromatic groups(e.g., phenyl groups). An exemplary ethoxylated phosphoric ester is apolyethylene phenyl ether phosphate. The second additive may have aspecific gravity (at 25° C.) that ranges from about 1.1 to about 1.35and a flash point of at least about 120° C. (e.g., about 130 to about170° C.). The second additive may exhibit a freezing point of at leastabout 40, and more specifically at least about 10° C. The secondadditive may also exhibit a freezing point of less than about −50, andmore specifically less than about −20° C. For example, the freezingpoint may range from about 40 to about −50, and more preferably fromabout 10 to −20° C. The second additive may exhibit a boiling point (at760 mm Hg) of at least about 110, and more specifically at least about140° C. The second additive may also exhibit a boiling point (at 760 mmHg) of less than about 190, and more specifically less than about 160°C. For example, the boiling point (at 760 mm Hg) may range from about110 to about 190, and more preferably from about 140 to 160° C. Thesecond additive may exhibit an acid number (KOH to first inflectionpoint), as measured for example according to ASTM D974-01, that rangesfrom about 90 to about 115, and more preferably from about 90 to about110. The second additive also may exhibit a nonionic content less thanabout 15, and more preferably less than about 7%. An exemplaryalkoxylated phosphoric ester is a polyethylene phenyl ether phosphate.

Examples of suitable additives having a phosphate content include,without limitation, a polyoxyethylene octadadecenyl ether phosphate(e.g., CAS number 9004-98-2, CAS number 7664-38-2, or LUBRHOPHOS® LB-400which is commercially available from Rhodia), polyoxyethylene laurylether phosphate (e.g., CAS number 39464-66-9 or LUBRHOPHOS® RD-510Ewhich is commercially available from Rhodia), a linear alcohol ethoxyphosphate (e.g., LUBRHOPHOS® LK-500 which is commercially available fromRhodia), a polyethylene phenyl ether phosphate (e.g., CAS No.39464-69-2) sold under the tradename LUBRHOPHOS® LP-700 which iscommercially available from Rhodia), a dialkylphenol phosphate ester(e.g., Rhodefac® RM-510 which is commercially available from Rhodia), orany combination thereof.

It is contemplated that the one or more additives having a phosphatecontent (e.g., first additive, second additive, or both) may be utilizedfor improving lubricity (e.g., antiwear properties) for fluid powersystems such as one disclosed in U.S. Pat. No. 5,152,926 (filed Sep. 10,1990, see e.g., col. 3, line 29 to col. 4, line 29), which is herebyincorporated by reference for all purposes, and for brake systems havingsilicone functional components such as one disclosed in U.S. Pat. No.4,744,915 (filed Aug. 24, 1987, see e.g., col. 2, lines 53-68), which ishereby incorporated by reference for all purposes. Accordingly, it isappreciated that the present invention may be incorporated into fluidpowers systems such as systems that generate, transmit, and controlapplications of power by using pressurized and moving fluids within anenclosed circuit (e.g., brake systems). Furthermore, it is appreciatedthat the one or more additives having a phosphate content of the presentinvention may be incorporated into a functional fluid that includes asilicone content, is essentially free of silicone (e.g., containssilicone at a concentration less than about 5 wt. %, preferably lessthan about 1 wt. %, more preferably less than about 0.1 wt. %, and mostpreferably less than about 0.01 wt. % based on the total weight of thefunctional fluid) or is free of silicone.

The additives having a phosphate content may be phosphate esters,phosphate esters, or both. Examples of suitable phosphate esters includephosphate monoesters, phosphate diesters, phosphate triesters, and anycombination thereof. The phosphate ester may include or consistessentially (e.g., contain at least 90 wt %, or at least 95 wt % basedon the total weight of the phosphate esters or the phosphate containingadditives) of one or more phosphate triesters. The phosphate ester maybe substantially or totally free of phosphate triesters and containphosphate monoesters, phosphate diesters, or both.

U.S. Pat. No. 4,755,316 (filed Oct. 23, 1987) TABLE D lists thefollowing examples of additives having a phosphate content, which may beused in the present functional fluid: phosphates, phosphate esters(bicresyl phosphate), phosphites, thiophosphates (zincdiorganodithiophosphates) chlorinated waxes, and halogen substitutedphosphorous compound. Additional examples of additives having aphosphate content include those described in U.S. Pat. No. 5,152,926(filed Sep. 10, 1990), see e.g., col. 3, line 29 to col. 4, line 29.These additives include: organic phosphates, such as Lubrizol™ 1097which is a zinc (dialkyl dithio) phosphate manufactured by the LubrizolCorporation; SYN-O-AD™ 8478, a 70%/30% blend of tri(2,4,6-tri-t-butylphenyl)phosphate/triphenyl phosphate manufactured by the StaufferChemical Company; an ethoxylated phosphate ester (Antara™ LP-700 type),a phosphate alcohol (ZELEC 3337 type), and a zinc dialkyldithiophosphate(e.g., Lubrizol 5139, 5604, 5178, 5186 type). Ethoxylated phosphateesters may be water soluble compositions having a phosphorus content offrom about 4 to 10 percent, preferably 5 to 7 percent, such asAntara™LP-700 of GAF (polyoxyethylene phenyl ether phosphate).Additional additives having a phosphate content include those describedin U.S. Pat. No. 4,744,915 (filed Aug. 24, 1987), e.g., col. 2, lines53-68, such as phosphate acid esters, trioctyl phosphate and tricreosolphosphate.

The first additive, the second additive, or both may be present at aconcentration greater than about 0.005 parts, preferably greater than0.010 parts, and more preferably greater than about 0.03 parts by weightof the total fluid composition. The first additive, the second additive,or both may be present at a concentration less than about 2.5 parts,preferably less than 0.7 parts, and more preferably less than about 0.3parts by weight of the total fluid composition. For example, the firstadditive, the second additive, or both may be present at a concentrationfrom about 0.005 to about 0.7 parts by weight of the fluid composition.

It is further appreciated the one or more additives may include knowncorrosion inhibitors such as the alkanol amines or alkyl amines andother organic amines to increase low temperature viscosity of functionalfluids (e.g., functional fluids containing borate esters), which in turnleads to the use of more complex and expensive additives such as thosedisclosed in EP0750033, filed Jun. 20, 1996, incorporated by reference(see, e.g. page 2, lines 55 to page 3, line 56) and EP0617116, filed onMar. 9, 1994, incorporated by reference (see e.g., page 2, lines 14 topage 3, line 7 and page 4, lines 1-16). By using small amounts of borateesters, the fluid compositions may use known corrosion inhibitors andstill achieve the desired low temperature viscosity. In addition,increased amounts of corrosion inhibitors and additives may be used toachieve improved stability or corrosion resistance without sacrificinglow viscosity. When included, the corrosion inhibitors may be present inthe amount of about 0 or about 0.005 to about 7, and more specificallyfrom about 0.1 to about 5 (e.g., from about 2 to about 4) parts byweight of the additive component.

Examples of corrosion inhibiting agents which may be used include thosedisclosed in EP Patent No. 0750033 (filed Jun. 20, 1996), such as aminescapable especially of neutralizing the boric ester, an amine containingat least one alkyl radical, especially from C1 to C7, or a cyclaneradical, especially from C5 to C7, or, again, an alkoxy radicalespecially from C1 to C6; an ethoxylated amines such as di-n-butylamine,tri-n-butylamine, diisopropanolamine of general formula:HN(CH₂CHOHCH₃)₂, monocyclohexylamine, dicyclohexylamine,2-amino-1-ethanol, diethanolamine of general formula: HN (CH₂—CH₂OH)₂,monomethanolmonopropylamine of general formula: HN(CH₂OH)(CH₂CH₂CH₃) ordiisopropylamine;an N-acyl derivative of sarcosine, for example theN-oleyl acylsarcosine marketed by Ciba Geigy under the name Sarkosyl 0™,benzotriazole, tolyltriazole, triphenyl phosphite, dodecenylsuccinicanhydride, bisphenol A, or polymerized trimethylquinoline.

Additional inhibitors disclosed in EP Patent No. 0617116 (filed Mar. 9,1994) include ether-amines having a molecular weight between 120 and 300(preferably between 150 and 250) and having the following formula:

in which R₃ is linear or branched radical having at least one etherfunctional group and no alcohol functional group, R is a methyl radicalor a hydrogen atom, p is an integer from 1 to 3 and q is an integer from0 to 2. The ether-amine used must contain a radical R₃ which is a linearor branched radical having at least one ether functional group and noalcohol functional group. Radical R₃ is not cyclic. R₃ may have thefollowing formula: R₁—O—R₂— in which R₁ is a linear or branched alkylradical preferably having from 1 to 5 carbon atoms and R₂ is a linear orbranched alkylene radical preferably having from 2 to 8 carbon atoms.The ether-amine comprises at least one and preferably at least 2 unitsderived from an epoxide. Advantageously, p+q may range from 1 to 3. Someor all of the ether-amine may have p+q=2. Furthermore, it is alsoadvantageous to use a mixture comprising by weight from 85 to 95% of anether amine having p+q=2 and from 15 to 5% of an ether-amine havingp+q=3. The ether-amine is generally obtained by reacting a startingether-amine, with an epoxide such as, for example, ethylene oxide,propylene oxide or a mixture of the two. The starting ether-amine canhave the following general formula (A): R₁—O—R₂—NH₂ in which R₁ and R₂have the same meaning as above. The ether-amine obtained advantageouslycontains the amines having the following formula (B):

which R₁, R₂, R, p and q have the same meaning as above (i.e., as forformula (A) above). In practice, a mixture of ether-amines having theformula (B) is obtained. It is desirable to obtain essentially the whichR₁, R₂, R, p and q have the same meaning as above. In practice, amixture of ether-amines having the formula (B) is obtained. It isdesirable to obtain essentially the amine having the formula (B) inwhich p=1 and q=1. An example of a suitable ether-amine is2,2′-[3(methoxypropyl)imino]bisethanol amine.

Examples of classes of corrosion inhibitors that may be used in thefunctional fluid compositions of the present invention include fattyacids such as lauric, palmitic, stearic or oleic acids, esters ofphosphorus or phosphoric acid with aliphatic alcohols, phosphates orphosphites such as ethyl phosphate, dimethyl phosphate, isopropylphosphate, butyl phosphite, triphenyl phosphite and diisopropylphosphite, alkenyl anhydride such as dodecenyl succinic anhydride(DDSA), di-(2-ethylhexyl)phosphoric acid (DEHPA), propanediamine andxylene component (e.g., Dupont Metal Deactivator comprising N,N′disalicylidene-1,2-propanediamine and xylene), poly(diethoxysiloxane)(e.g., PSI-021), hydroxyethylpiperazine (e.g., dihydroxyethylpiperazine), propylene glycol and borax 5 mol component, heterocyclicnitrogen containing compounds such as benzotriazole or its derivativesor any combination, such compounds optionally with 1,2,4 triazole and/orits derivatives (see U.S. Pat. No. 6,074,992 (e.g., column 2, line 65 tocolumn 3, line 12) filed Feb. 2, 1999 by Pierre Levesque and GB PatentNo. British Patent No. 1,111,680 (e.g., page 1, line 10 to page 2, line8) filed Dec. 1, 1965, by McPhail et. al., both hereby incorporated byreference). Other amine compounds useful as corrosion inhibitors includealkyl amines such as di-n-butylamine and di-n-amylamine, cyclohexylamineand salts thereof. Amine compounds which are particularly useful ascorrosion inhibitors in the functional fluid compositions of the presentinvention include the alkanol amines, preferably those containing one tothree alkanol groups with each alkanol group containing from one to sixcarbon atoms. Examples of useful alkanol amines include mono-, di- andtrimethanolamine, mono-, di- and triethanolamine, mono-, di- andtripropanolamine and mono-, di- and triisopropanolamine.

Examples of 1,2,4 triazoles and its derivatives include those listed inU.S. Pat. No. 6,074,992 (column 2, line 65 to column 3, line 12) filedFeb. 2, 1999 by Pierre Levesque, such as 1,2,4 triazole or itsderivatives represented by the formula:

wherein R and R′ are the same or different and can be hydrogen, an alkylgroup containing from 1 to 8 carbon atoms, an amino group such as —NH,—NHR or —NR R′, an acyl group such as —COR, or an aryl group such asbenzene or toluene.

Without limitation, additional examples of 1,2,4 triazoles and itsderivatives include those listed in GB Patent No. British Patent No.1,111,680 (page 1, line 10 to page 2, line 8) filed Dec. 1, 1965, byMcPhail et. al. such as 1,2,4-triazoles having the formula

wherein R₁, R₂, R₃ and R₄=hydrogen, alkyl, aryl, alkaryl, aralkyl,cycloalkyl, acyl or aroyl, the symbol (R₄) meaning that the substituentR₄ is attached to any one of the nitrogen atoms comprising the triazolering or is a labile substituent if R₄ is hydrogen. Thus, the formularecited above embraces, for example, not only 3-substituted- and3,5-substituted-1,2,4-triazoles, for example 3-amino-1,2,4-triazole,3-amino-5-heptyl-1,2,4-triazole, but also acylated andaroylated-1,2,4-triazoles which may be

for example benzoylated-5-phenyl-1,2,4-triazole, which may be

The additive components may also advantageously contain, in addition toone or more corrosion inhibitors, other additive compounds such asantifoaming agents, pH stabilizers, antioxidants and the like, all wellknown to the skilled formulator for enhancing the performance of thefunctional fluid composition.

It is contemplated that other materials may be formulated into thefunctional fluids of the present invention so long as care is taken notto lower ERBP or WERBP temperatures and particularly lubricity belowacceptable levels or to increase the low temperature viscosity above anacceptable level. For example, the functional fluids of the presentinvention may include from about 0 or 0.10 parts by weight to about 30parts by weight, based on the total weight of the composition, of adiluent or a lubricant such as, for example, polyethylene oxides,polypropylene oxides, polyglycols (e.g. mixtures of monoethylene glycol,diethylene gycol, triethylene glycol tetraethylene glycol, and highermol adducts of ethylene glycol), poly(alkylene oxides) dialkoxyglycols,borate co-esters, or any combination thereof. One preferred lubricantsuch as a polyalkylene glycol monobutyl ether is present in the amountfrom about 10 to about 30, and more preferably in an amount of about 15to about 25 parts by weight of the functional composition. An example ofa preferred polyalkylene glycol monobutyl ether (which contains twodifferent alkylene glycol repeat units, oxyethylene and oxypropylene, atabout equal weights and n is at least four) is sold under the tradenameUCON™ 50-HB-260, commercially available from The Dow Company.

It is also contemplated that the teachings of the present inventioncould be applied to other fluids formulated to achieve lower viscositiessuch as those disclosed in U.S. Pat. No. 4,371,448, EP0 750033 andEP0617116 (hereby incorporated by reference for all purposes) to furtherlubricity while maintaining acceptable minimum ERBP and WERBPtemperatures.

The functional fluids of the present invention may meets the needs inthe art for high performance functional fluids having high lubricity toreduce or eliminate brake noise, while improving the life of the brake.The functional fluids of the present invention include brake fluids thatmeet all of the requirements for DOT 3 and DOT 4 fluids given in FederalMotor Vehicle Safety Standards 116, having high boiling points (e.g.ERBP above 203° C. and 230° C., respectively) and also having reducedkinematic viscosity at −40° C., below 1500 cSt and 1800 cSt,respectively. The novel functional fluids of the present invention maymeet all of the requirements for DOT 3 and DOT 4 fluids given in FederalMotor Vehicle Safety Standards 116 and have improved lubricity (e.g.,antiwear).

Fluid compositions of the present invention have an ERBP of at leastabout 205° C., preferably at least about 225° C., more preferably atleast about 240° C., and most preferably at least about 245° C. The lowtemperature viscosity at −40° C. of the fluid composition is preferablyless than 1500 centistokes (cSt), preferably less than about 1200 orabout 1100 centistokes (cSt), more preferably less that about 1000 cStor about 900 cSt, and possibly less than about 850 cSt.

EXAMPLE FORMULATION

The following example as shown in Table 2 is not intended to be limitingand illustrates a certain preferred embodiment of the present invention.D500 is a polyethylene-propylene glycol monomethyl ether having anaverage molecular weight of about 500 having n of at least 4, pusher isa mixture of polyethylene glycols having n of at least 4, PSI-021 is apoly(diethoxysiloxane) available from Gelest Inc. (Morrisville, Pa.,USA), and Butyl Carbitol™ solvent is a diethylene glycol monobutyl etheravailable from The Dow Chemical Co. (USA). Intermediate 1 contains about45 wt. % Butyl Carbitol™ Solvent, about 12.5% monoethylene glycol, about9.4 wt. % Agerite Resin D, about 1.25 wt. % sodium nitrate, about 0.65wt. % benzotriazole, and about 31.2 wt. % butyl diethanolamine.Intermediate 2 contains about 88 wt. % propylene glycol and about 12 wt.% sodium borate (e.g., Borax 5 Mol).

By way of example, the functional fluids of Table 2 which include acommercial DOT 3 brake fluid (Comparative Example 1) and newly developedfunctional fluids (Examples 1-3), are evaluated for lubricity. Thelubricity properties of these fluids are shown in Table 3. Table 3illustrates that Comparative Example 1 has a relatively large scar widthand a relatively high average tooth count, indicating low lubricity,while the newly developed fluids (Examples 1-3) have higher lubricitythan Comparative Example 1, with Example 1 having the highest lubricity(lowest scar width). Example 1 also has the lowest average tooth count.

TABLE 2 Comparative Ingredient Example 1 Example 1 Example 2 Example 3Butyl CARBITOL ™ Solvent 2.9000% 2.8942% 2.9000% 2.8942% MTG(methoxytriglycol) 53.1450% 53.0387% 46.0400% 45.9479% BTG(butoxytriglycol) 9.0000% 8.9820% 9.0000% 8.9820% Methoxypolyglycol(MPGr) - refined 12.0000% 11.9760% 12.0000% 11.9760% not basic UCON ® 50HB-260 20.0000% 19.9600% D500 20.0000% 19.9600% Pusher 7.0000% 6.9860%Intermediate A 1.6000% 1.5968% 1.6000% 1.5968% Intermediate B 0.5900%0.5888% 0.5900% 0.5888% DDSA (dodecenyl succinic anhydride) 0.1500%0.1497% 0.1500% 0.1497% DEHPA (di-2-ethyl hexyl phosphoric 0.1000%0.0998% 0.1000% 0.0998% acid) Dupont metal deactivator 0.0100% 0.0100%0.0100% 0.0100% PSI-021 (polydiethoxysiloxane) 0.0050% 0.0050% 0.0050%0.0050% Hydroxyethylpiperazine 0.5000% 0.4990% 0.5000% 0.4990%(dihydroxyethyl piperazine) Oleic acid 0.1050% 0.1048% LUBRHOPHOS ®LP-700 0.2000% 0.2000% Total 100.0000% 100.0000% 100.0000% 100.0000%

TABLE 3 Average Scar Average Fluid Test Condition Width, mm Tooth CountComparative 45.4 kg break in, 90.9 kg 0.5385 19 Example 1 load for 30minutes Example 1 45.4 kg break in, 90.9 kg 0.1880 0 load for 30 minutesExample 2 45.4 kg break in, 90.9 kg 0.3350 8 load for 30 minutes Example3 45.4 kg break in, 90.9 kg 0.2875 5 load for 30 minutes

Lubricity (e.g., antiwear) of functional fluids may be determined usingthe Falex Pin & Vee Block Test Machine according to a modified ASTM D2670. By way of example, lubricity is evaluated for compositions of thepresent invention. For the purposes of this evaluation, a load of 100 lbis applied and maintained for a break in time of 1 minute. The load isincreased and maintained at 200 lb for a remaining test duration of 30minutes. Thereafter, wear is determined and recorded as the measuredwidth of the Vee Block scaring, (e.g., average scar width), the numberof teeth of the ratchet mechanism advanced to maintain a constant loadduring a prescribed test time interval, (e.g., average tooth count), orboth. Higher reported numbers (e.g., average scar width and averagetooth count) correlate to higher degrees of wear.

The functional fluid of the present invention will impart improvedlubricity for a fluid power system as determined from an average scarwidth according to modified ASTM D 2670 (100 pounds break-in for 1minute, 200 pounds load for 30 minutes), an average tooth countaccording to modified ASTM D 2670 (100 lb break-in for 1 min, 200 lbload for 30 mins), or both. The functional fluid may exhibit an averagescar width of at least about 0.05, more specifically at least about 0.1mm. The functional fluid also will exhibit an average scar width lessthan about 0.45, specifically less than about 0.35, and morespecifically less than about 0.3 mm. For example, the average scar widthmay range from about 0.05 to about 0.45, more specifically from about0.1 to about 0.3 mm. Furthermore, the functional fluid may exhibit anaverage tooth count of less than about 15, and more specifically lessthan about 8.

The formulation for the functional fluids are analyzed to measure thephysical properties relating to DOT 3 brake fluid requirements. Thephysical properties (using the test procedures set forth in the FederalMotor Vehicle Standard 116 found at §571.116 et seq.) are shown in Table4. It is also surprisingly seen in Example 2 and Example 3 that apolyethylene-propylene glycol monoalkyl ether (e.g., apolyethylene-propylene glycol monomethyl ether having an averagemolecular weight of about 500) such as D500 (e.g., at a concentrationfrom about 10 wt. % to about 30 wt. %, more preferably from about 17 wt.% to about 23 wt. % based on the total weight of the functional fluid),a monounsaturated fatty acid such as oleic acid (e.g., at aconcentration from about 0.02 wt. % to about 0.5 wt. %, preferably fromabout 0.08 wt. % to about 0.15 wt. % based on the total weight of thefunctional fluid) or both may also be used in combination with methoxytriglycol preferably at a concentration greater than about 25 wt. %,more preferably from about 40 wt. % to about 60 wt. % (and preferably incombination with an ethoxylated phosphate ester, and more preferably incombination with a polyethylene phenyl ether phosphate such asLUBRHOPHOS® LP-700) in functional fluids having one or any combinationof the following characteristics: an average scar width less than about0.36 mm, a tooth count less than about 10, an ERBP greater than about250° C., or a viscosity at −40° C. of less than about 800 cSt(preferably less than about 780 cSt).

TABLE 4 Comparative Exam- Example 1 ple 1 Example 2 Example 3 ERBP, ° C.249 249 253 253 Viscosity @−40° C., cSt 821 821 776.7 777

Functional fluids of the present invention are well suited for use as ahydraulic fluid for numerous mechanical systems (e.g., hydraulic lifts,cranes, forklifts, bulldozers, hydraulic jacks, brake systems,combinations thereof, or the like). The high lubricity as well as ERBP,WERBP, and low temperature viscosity of these fluid compositions arewell-suited for brake systems in transportation vehicles (e.g., fixedand rotary wing aircraft, trains, automobiles in classes 1 to 8, or thelike). These braking systems include anti-lock braking systems (ABS),stability control systems, or combinations thereof. Thus, the presentinvention includes any of these systems which include the fluidcompositions disclosed herein.

Traditional automotive brake systems include a depression mechanismoperably connected to a master cylinder, a pneumatic or hydraulicbooster, brake lines, and a braking mechanism. To operate the brakes, anoperator presses the depression mechanism and the master cylinderapplies a pressure to the brake fluid that is transmitted through thebrake lines to the braking mechanism that at least partially resists themotion of the wheel or wheels. Traditional brake systems require abooster pump to increase the pressure applied to the brake fluid toadequately operate the braking mechanism (e.g., to avoid a collision,when one or more wheels is slipping on a road surface, or combinationsthereof due to the high viscosity of traditional brake fluids.

Brake systems of the present invention may include low viscosityfunctional fluids described above, traditional higher viscosity brakefluids, or any combination thereof. Preferred brake systems includebrake fluids that consist essentially of the low viscosity functionalfluids described above. Furthermore, brake systems of the presentinvention may optionally include a booster pump (e.g. a pre-chargebooster pump); however, the booster pump is preferably not included inthe brake system as the use of the presently disclosed brake fluid maymake the booster pump extraneous. Exclusion of the booster pump wouldrepresent a cost savings over systems where a booster pump was required.

It should be understood that various ingredients may be substituted,added, or removed from the above formulations without departing from thescope of the present invention. Moreover, it is contemplated that theweight concentrations of the above ingredients and the values of theproperties listed may vary up to or greater than 5%, 10%, 25%, or 50% ofthe values listed. For example, a value of 10 may vary by 10%, which mayresult in a range of about 9 to about 11.

It will be further appreciated that functions or structures of aplurality of components or steps may be combined into a single componentor step, or the functions or structures of one-step or component may besplit among plural steps or components. The present inventioncontemplates all of these combinations. Unless stated otherwise,dimensions and geometries of the various structures depicted herein arenot intended to be restrictive of the invention, and other dimensions orgeometries are possible. Plural structural components or steps can beprovided by a single integrated structure or step. Alternatively, asingle integrated structure or step might be divided into separateplural components or steps. In addition, while a feature of the presentinvention may have been described in the context of only one of theillustrated embodiments, such feature may be combined with one or moreother features of other embodiments, for any given application. It willalso be appreciated from the above that the fabrication of the uniquestructures herein and the operation thereof also constitute methods inaccordance with the present invention. The present invention alsoencompasses intermediate and end products resulting from the practice ofthe methods herein. The use of “comprising” or “including” alsocontemplates embodiments that “consist essentially of” or “consist of”the recited feature.

The explanations and illustrations presented herein are intended toacquaint others skilled in the art with the invention, its principles,and its practical application. Those skilled in the art may adapt andapply the invention in its numerous forms, as may be best suited to therequirements of a particular use. Accordingly, the specific embodimentsof the present invention as set forth are not intended as beingexhaustive or limiting of the invention. The scope of the inventionshould, therefore, be determined not with reference to the abovedescription, but should instead be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. The disclosures of all articles and references,including patent applications and publications, are incorporated byreference for all purposes.

1. A functional fluid composition for imparting lubricity in a fluidpower system having metal/rubber contact comprising: about 50 parts byweight to about 99 parts by weight of a glycol component; and about 0.3parts by weight to about 10 parts by weight of one or more additivesincluding a phosphate content; wherein the functional fluid compositionexhibits an average scar width as measured according to ASTM D 2670 (100lb break-in for 1 min, 200 lb load for 30 minutes) less than about 0.35mm, an average tooth count according to ASTM D 2670 (100 lb break-in for1 min, 200 lb load for 30 minutes) of less than about 15, or both, andwherein the functional fluid is optionally free of silicone; wherein theone or more additives includes (i) a first additive including an esterof phosphoric acid, (ii) a second additive including an ethoxylatedphosphate ester, or (iii) both (i) and (ii).
 2. The functional fluidcomposition of claim 1, wherein the first additive consists essentiallyof a tricresyl phosphate.
 3. The functional fluid composition of claim2, wherein the second additive includes an ethoxylated phosphate esterselected from the group consisting of a polyoxyethylene octadadecenylether phosphate. a polyoxyethylene lauryl ether phosphate, a linearalcohol ethoxy phosphate, a polyethylene phenyl ether phosphate, adialkylphenol phosphate ester or any combination thereof.
 4. Thefunctional fluid composition of claim 3, wherein the second additiveincludes a polyethylene glycol phenyl ether phosphate.
 5. The functionalfluid composition of claim 3, wherein the second additive consistsessentially of a polyethylene glycol phenyl ether phosphate.
 6. Thefunctional fluid composition of claim 3, wherein the first additiveexhibits a melting point that ranges from about −45° C. to about −25°C., a boiling point (at 4 mm Hg) that ranges from about 230° C. to about265° C., a flash point that is at least about 375° C., a specificgravity (at 25° C.) that ranges from about 1.1 to about 1.25, and anacid number of less than about 0.5 mg KOH/kg of the first additive. 7.The functional fluid composition of claim 3, wherein the second additiveexhibits an acid number (KOH to first inflection point) that ranges fromabout 90 to about 115 mg KOH/kg of the second additive and a nonioniccontent less than about 15%.
 8. The functional fluid composition ofclaim 3, wherein the first additive, the second additive, or both ispresent in the amount of about 0.005 to about 0.7 parts by weight of thefluid composition.
 9. The functional fluid composition of claim 3,wherein the one or more additives includes a corrosion inhibitor that ispresent in the amount of about 0.5 parts by weight to about 2 parts byweight of the one or more additives.
 10. The functional fluidcomposition of claim 6, wherein the glycol component comprises theformula:

wherein R₁ is H or an alkyl group containing 1 to 8 carbon atoms ormixtures thereof, the glycol component including at least one glycolwherein at least one of R₂, R₃, R₄, and R₅ is an alkyl group containing1 to 8 carbon atoms.
 11. The functional fluid composition according toclaim 10, wherein the glycol component includes at least one glycolhaving at least one first repeat unit wherein R₂, R₃, R₄, and R₅ areeach H and at least one second repeat unit wherein at least one (e.g.,one, two, three, or all four) of R₂, R₃, R₄, and R₅ are each an alkylgroup containing 1 to 8 carbon atoms.
 12. The functional fluidcomposition according to claim 10 wherein the at least one glycolinclude glycol where n=2 is present in an amount of from about 0.25parts by weight to about 10 parts by weight of the glycol component andglycol where n=4 or more in an amount from about 0 parts by weight toabout 30 parts by weight of the glycol component.
 13. The functionalfluid composition according to claim 10 wherein the composition issubstantially free of glycol borate esters.
 14. The functional fluidcomposition according to claim 10 further comprising from about 0.1parts by weight to about 70 parts by weight of a glycol borate estercomprising the formula:

wherein each R₁ R₂, R₃, R₄, and R₅ is independently H or an alkyl groupcontaining 1 to 8 carbon atoms or mixtures thereof, n is 1 to
 4. 15. Thefunctional fluid composition according to claim 10 wherein the glycolcomponent comprises one or more high purity glycol components.
 16. Thefunctional fluid composition according to claim 10 wherein: about 0.5parts by weight to about 10 parts by weight of the glycol component hasR₁ contains 4 carbon atoms and n=2; about 40 parts by weight to about 60parts by weight of the glycol component has R₁ contains 1 carbon atomand n=3; about 5 parts by weight to about 15 parts by weight of theglycol component has R₁ contains 4 carbon atoms and n=3; about 5 partsby weight to about 15 parts by weight of the glycol component wherein R₁contains 4 carbon atoms and n=4 or more; about 0.3 parts by weight toabout 10 parts by weight of one or more additives including a phosphatecontent, wherein the functional fluid composition exhibits an averagescar width according to ASTM D 2670 (100 lb break-in for 1 min, 200 lbload for 30 minutes) that ranges from about 0.1 mm to about 0.3 mm, anaverage tooth count according to ASTM D 2670 (100 lb break-in for 1 min,200 lb load for 30 minutes) of less than about 8, or both.
 17. Thefunctional fluid composition according to claim 10, wherein thefunctional fluid composition is free of silicone.
 18. The functionalfluid composition according to claim 10, wherein the fluid power systemis a brake system.
 19. An additives package for imparting lubricity in afluid power system comprising: about 5 parts by weight to about 75 partsby weight of at least one of (i) a first additive including an ester ofphosphoric acid and (ii) a second additive including an ethoxylatedphosphate ester; about 30 parts by weight to about 99 parts by weight oftwo or more corrosion inhibitors that includes at least one of (a)propanediamine and xylene, (b) hydroxyethylpiperazine, (c) dodecenylsuccinic anhydride, (d) Di-(2-ethylhexyl)phosphoric acid, (e)poly(diethoxysiloxane), (e) oleic acid, and (f) propylene glycol andborax 5 mol component, wherein the first additive exhibits a meltingpoint that ranges from about −45° C. to about −25° C., a boiling point(at 4 mm Hg) that ranges from about 230° C. to about 265° C., a flashpoint that is at least about 375° C., a specific gravity (at 25° C.)that ranges from about 1.1 to about 1.25, and an acid number of lessthan about 0.5 mgKOH/kg, wherein the second additive exhibits an acidnumber (KOH to first inflection point) that ranges from about 90 toabout 115 and a nonionic content less than about 15%, and wherein afunctional fluid composition includes the additive package, thefunctional fluid composition exhibits an average scar width according toASTM D 2670 (100 lb break-in for 1 min, 200 lb load for 30 minutes) ofless than about 0.35 mm, an average tooth count according to ASTM D 2670(100 lb break-in for 1 min, 200 lb load for 30 minutes) of less thanabout 15, or both.
 20. The additive package of claim 19, wherein thefirst additive consists essentially of a tricresyl phosphate.
 21. Theadditive package of claim 20, wherein the second additive consistsessentially of a polyethylene glycol phenyl ether phosphate.
 22. Amethod for imparting lubricity comprising the steps of: contacting oneor more rubber components of a fluid power system with a functionalfluid composition free of silicone and including about 0.3 parts byweight to about 10 parts by weight of one or more additives including aphosphate content, wherein the functional fluid composition exhibits anaverage scar width according to ASTM D 2670 (100 lb break-in for 1 min,200 lb load for 30 minutes) that ranges from about 0.05 mm to about 0.45mm, an average tooth count according to ASTM D 2670 (100 lb break-in for1 min, 200 lb load for 30 minutes) of less than about 15, or both.
 23. Afunctional fluid composition for imparting lubricity in a fluid powersystem having metal/rubber contact comprising: about 50 parts by weightto about 99 parts by weight of a glycol component; and about 0.3 partsby weight to about 10 parts by weight of one or more additives; whereinthe functional fluid is further characterized either or both of i) theglycol component includes a polyethylene-propylene glycol monomethylether having an average molecular weight of about 500 at a concentrationfrom about 10 wt. % to about 30 wt. % based on the total weight of thefunctional fluid; or ii) the one or more additives includes oleic acidat a concentration from about 0.02 wt. % to about 0.5 wt. % based on thetotal weight of the functional fluid; wherein the one or more additivesoptionally contains a polyethylene phenyl ether phosphate, thefunctional fluid is optionally is free of silicone, the glycol componentincludes methoxytriglycol present a concentration greater than about 25wt. % based on the total weight of the functional fluids, and thefunctional fluid has one or any combination of the followingcharacteristics: an average scar width less than about 0.36 mm, a toothcount less than about 10, an ERBP greater than about 250° C., or aviscosity at −40° C. of less than about 800 cSt.